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Biomedical subjects

M H Lewis

Publications and source records attributed to M H Lewis.

At least 91 records · Page 5Linked to original sources
PubMed1996

Prevalence of abdominal aortic aneurysm in a hypertensive population.

Two studies were undertaken to estimate the prevalence of abdominal aortic aneurysm in a hypertensive population. The initial study screened hypertensive people from three local general practices. In this study 918 patients underwent ultrasound scanning of the abdominal aorta (498 men and 420 women). A total of 24 abdominal aortic aneurysms were identified; 20 in men (4%) and four in women (0.9%). Of these, 11 were > 4 cm in transverse diameter. Following this study, only hypertensive men over the age of 60 years and women over the age of 65 years were screened from a total of 29 general practices. Regular scanning sessions were held at each practice and 1328 patients attended (744 men and 584 women). A total of 43 abdominal aortic aneurysms were detected; 39 in men (5.2%) and four in women (0.7%). Hypertensive men are at increased risk of developing abdominal aortic aneurysms and should be offered an initial ultrasound scan at 60 years of age. Female hypertensives yield a much lower detection rate and screening hypertensive females would probably be an inappropriate use of available resources.

Age Distribution↗
PubMed1995

Rearing conditions alter social reactivity and D1 dopamine receptors in high- and low-aggressive mice.

As a result of selective breeding, NC900 mice exhibit isolation-induced attacks in a social interaction test, whereas NC100 mice do not attack but freeze instead. Administration of the D1 receptor agonist dihydrexidine was previously shown to reduce aggression in NC900 mice and nonagonistic approaches in NC100 mice. This resulted from induction of a marked social reactivity in both selected lines. Because isolation rearing also induces social reactivity, the present experiment was designed to test the hypothesis that D1 dopamine receptors mediate isolation-induced social reactivity. Isolation was expected to potentiate the effects of a D1 agonist and to increase D1 dopamine receptor density. Thus, isolated and group-reared mice were administered dihydrexidine, and their social behavior was compared to vehicle-injected controls. Dihydrexidine induced higher levels of reactivity among isolated than among group-reared animals, especially in NC900 mice. In independent experiments, increased densities of D1 dopamine receptors in the striatum of isolated animals were found, with no change in affinity. These studies suggest an important role for the D1 dopamine receptor as a mediator of isolation-induced social reactivity.

Aggression↗
PubMed1995

Blink rate as an index of dopamine function in adults with mental retardation and repetitive behavior disorders.

Direct observation of blink rate was used as a noninvasive, in vivo estimate of dopamine function in adults with mental retardation and repetitive behavior disorders. Blink rate as measured in groups of stereotypy, compulsion, and control subjects was highly stable. Subjects with stereotypies had significantly lower blink rates than did control subjects. Although blink rates for compulsive subjects were not significantly different from those of control subjects, a subgroup of compulsive subjects with comorbid stereotypic behaviors displayed significantly lower blink rates. Significant inverse correlations were found for blink rate and severity of repetitive behavior disorder and for blink rate and ratings of motor slowness. These findings support the hypothesis that stereotyped behavior among adults with mental retardation is mediated by hypodopaminergic function.

Adult↗
PubMed1995

Exploration of the common bile duct for stones: the influence of the flexible choledochoscope and perioperative antibiotic prophylaxis.

A retrospective study of 110 patients, out of a total of 743 open cholecystectomies, who have undergone common bile duct (CBD) exploration for stones between 1985 and 1990. CBD exploration was performed in the presence of abnormal peroperative cholangiogram in 86 (78%) patients. The remaining 24 patients were known to have either an abnormal preoperative ERCP or palpable ductal stones at the time of surgery. Post exploratory choledochoscopy was performed as an additional completion procedure in 58 (53%) patients and it identified further stones in 28 (48.3%) of these patients. There were three patients in whom no stones were identified on exploration of the CBD. Documented evidence of peroperative antibiotic prophylaxis was obtained in 78 (71%) patients. A total of 27 (24.5%) patients developed complications including seven (6.4%) patients with retained stones. In four of these patients with retained stones, flexible choledochoscopy was undertaken as an additional completion procedure to ensure ductal clearance. Cardiorespiratory and septic complications were the next most common problems occurring in 6.5% and 5.4% respectively, of patients reviewed. In conclusion, the retained stone rate has fallen from 14% in 1987 to 6.4% in this study. The choledochoscope has influenced this as it identified further residual stones following conventional exploration. The sepsis rate has also fallen from 19.5% to 4.5% in this study. We believe this is due to the use of antibiotic prophylaxis.

Adult↗
PubMed1995

Compulsions in adults with mental retardation: prevalence, phenomenology, and comorbidity with stereotypy and self-injury.

A variety of conceptual similarities between compulsions seen in individuals with obsessive compulsive disorder and stereotypy and self-injury seen in individuals with mental retardation led us to investigate the prevalence, phenomenology, and comorbidity of compulsions in adults with severe or profound mental retardation. We developed simple assessment screening instruments for stereotypy and self-injury and used Gedye's Compulsive Behavior Checklist and found acceptable levels of reliability, stability, and validity for each instrument. Prevalences were as follows: stereotypy: 60.9%; self-injury: 46.6%; and compulsion: 40%. The occurrence of compulsions was significantly positively associated with the occurrence of stereotypy, self-injury, and stereotypy plus self-injury.

Adolescent↗
PubMed1995

Clomipramine treatment for stereotype and related repetitive movement disorders associated with mental retardation.

The efficacy of the serotonin uptake inhibitor clomipramine in the treatment of stereotyped and related repetitive behavior disorders was tested in individuals with severe and profound mental retardation. A double-blind, placebo-controlled crossover trial of clomipramine was associated with significant reductions in the frequency and intensity of stereotyped behavior and teacher ratings of stereotypy, hyperactivity, and irritability as well as increased adaptive engagement and decreased staff intervention for nontargeted behavior problems. Adverse effects occurred in 3 of the 10 subjects. Of the 7 subjects who tolerated the drug, 6 exhibited a clinically significant improvement in one or more repetitive behaviors. Our results provide support for the hypothesis that clomipramine is effective in treating stereotyped and related behaviors associated with mental retardation.

Adolescent↗
PubMed1994

Association of genetic differences in social behavior and cellular immune responsiveness: effects of social experience.

We have recently demonstrated that selective breeding of ICR mice for differences in social behavior (i.e., high versus low levels of social isolation-induced aggression) are related to increased susceptibility to tumor development and reduced levels of natural killer (NK) cell activity. In the present investigation, we sought to extend examination of the line differences in immune status to T and B cell responsiveness. In addition, we also sought to determine if social experience contributes to line differences in immune responsiveness. A cosibial design was used to examine whether single vs group housing modified the magnitude of line differences in immune status. Compared to aggressive (NC900) mice, nonaggressive (NC100) mice had significantly lower T cell proliferative responses to concanavalin A, lower IL-2 and gamma-interferon production, as well as significantly lower NK activity. Of the various measures of cellular immune responsiveness, housing condition was found to have a significant effect only on NK activity. No significant line by housing interactions were found for any of the immune measures tested. The present data demonstrate that the genetic selection for differences in social behavior is associated with line differences in several parameters of cellular immune responsiveness. These mouse lines provide a valuable research model to examine the association between selection for genetic differences in social behavior and differences in immune responsiveness.

Animals↗
PubMed1994

Social reactivity and D1 dopamine receptors: studies in mice selectively bred for high and low levels of aggression.

Robust individual differences in social behavior have been obtained by selectively breeding Institute for Cancer Research mice for high and low levels of aggression. As previously shown, when paired with a non-selected group-housed partner mouse, NC900 mice exhibit isolation-induced aggression. Conversely, NC100 mice fail to attack, freezing upon social contact. Previous studies have established that NC100 mice have lower dopamine concentrations in nucleus accumbens and caudate nucleus, with increased dopamine receptor densities in these same regions. Thus, we wished to determine the effect of administration of a dopamine receptor agonist on social behavior. Mice of both lines were administered 0, 1, 3, or 10 mg/kg (SC) of the full efficacy D1 receptor agonist dihydrexidine, and their behavior was assessed in a social interaction test. Dihydrexidine reduced aggression in NC900 mice and nonagonistic approach in NC100 mice in a dose dependent manner. In both cases, this resulted from induction of a marked reactivity to mild social stimulation as measured by increases in behaviors such as escape, reflexive kicking, and vocalizations. Dihydrexidine had no systematic effect on the freezing behavior characteristic of the low-aggressive line. In independent experiments, mice were pretreated with either the D1 antagonist SCH-23390 (.1 mg/kg) or the selective D2 antagonist remoxipride (1.0 mg/kg), after which they received dihydrexidine (10 mg/kg) and were tested as above. The effects of dihydrexidine on social reactivity in mice of both lines were significantly antagonized by SCH-23390 but not attenuated by remoxipride.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1994

An 11-year experience of arterial embolectomy in a district general hospital.

We present a retrospective audit of all arterial embolectomies performed at the East Glamorgan General Hospital over an 11-year period (1980-1990). Eighty-seven patients (47M:40F), mean age 67 years (50-90 years) underwent 95 embolectomies, an incidence consistent with previous studies. There were 17 upper and 71 lower limb emboli with a mean delay before diagnosis of 29 h (range 1-264 h). In 66% of cases the cause was atrial fibrillation; 33% received immediate heparinization and 14% prophylactic antibiotics. Surgery was performed by a consultant in 12 and registrars in 75 cases, and under local anaesthesia in 80% and general anaesthesia in 20%. There was no anaesthetist present in 54% of cases. Few pre- or peroperative arteriograms were performed. The 30-day mortality was 45%, with an amputation rate of 15% and an overall postoperative complication rate of 62% with little improvement in these figures over the last 10 years. Factors increasing mortality were: delay before diagnosis, grade of surgeon performing the operation, and inadequate inflow or outflow at operation. Factors found to affect limb salvage rate adversely were a history of intermittent claudication, although such a history was not recorded in many cases, and lack of immediate preoperative heparinization. Although embolectomy is considered a 'registrar operation', reviewing our results it can be seen that it is an uncommon operation, in our series eight or nine being performed annually. Sometimes inappropriate surgery is performed upon patients in whom severe systemic illness may contraindicate any form of surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗